Fusible materials that melt upon heating and resolidify upon subsequent cooling are well known. They may be natural, for example wax, or synthetic, for example thermoplastic or glass. Metallic containers of a wide variety of shapes and constructions are also known. Self-heating product containers with single-use chemical heaters and employing user-initiated chemical heating are well known. U.S. Pat. Nos. 5,461,867 and 5,626,022, for example, disclose single-use heaters employing the exothermic hydration of calcium oxide. U.S. Pat. No. 5,035,230 discloses single-use heaters employing the reaction of a polyol fuel such as ethylene glycol with an oxidizing agent such as potassium permanganate. Following activation by a user to cause the mixing of reaction components, chemical heaters produce a fixed quantity of heat and thereby cause a temperature rise dependent on the rate of heat generation by the reaction and the rate of heat loss from the heater to the product being heated and, to one extent or another, to the surroundings. Depending on the chemical reaction employed, there are methods and materials that may be employed in heater manufacture to tailor the rate and duration of an exothermic reaction to achieve a desired magnitude of temperature rise in the product being heated.